Selectivity and potential interference from phenolic compounds in chemiluminescence methods for the determination of synephrine

Abstract

Three recently reported chemiluminescence methods (based on reactions with alkaline luminol and hexacyanoferrate(III); acidic cerium(IV) and rhodamine B; and acidic permanganate with polyphosphates) for the determination of synephrine were re-evaluated in terms of their selectivity towards this analyte in comparison to other phenolic compounds. A fourth reagent system, acidic soluble manganese(IV) and formaldehyde, was also examined. Each set of reagents was sensitive towards synephrine (limits of detection were 3 × 10 -9 , 5 × 10 -8 , 1 × 10 -8 and 1 × 10 -8 mol/L, respectively) but also responded with numerous other phenolic compounds, including some that are present in citrus fruit extracts, dietary supplements and/or biological fluids. It is therefore recommended that the determination of synephrine in these matrices should incorporate physical separation of sample components (e.g. chromatography or electrophoresis). In more general terms, this study illustrates that accurate percentage recoveries for an analyte in spiked samples (without validation against another analytical method) are insufficient to confirm the analytical utility of new flow-injection analysis (FIA) procedures.

Chemiluminescence and electrochemiluminescence detection of controlled drugs

“…There are many reports of chemiluminescence from the reaction of various organic compounds with oxidants such as cerium(IV),94–96 hexacyanoferrate(III),97, 98 and hypohalites 3, 99. Unlike permanganate and manganese(IV) in acidic solution, the emitting species in these reactions often appears to be derived from the organic analyte, or generated by energy transfer from a reaction intermediate to a more efficient luminophore (e.g.…”

A stopped‐flow study of the dual chemiluminescence for the luminol–KIO4–Mn2+ system in strong alkaline solutions

“…Singlet oxygen could be produced through the reaction of periodate with the primary ROS (e.g. O 2 − or HO 2 − ) (24,25) generated in eqns (1)-(3) as described in eqns (6) and (7).…”

“…Firstly, the delay time for the start of the second CL peak (Fig. 1) is probably a result of CL emission generated from the secondary ROS [eqns (5)- (7)]. Secondly, the second CL peak will not be observable unless the concentration of KIO 4 is above a certain level (Fig.…”

“…Certain phenolic compounds exhibit intense CL emission for some CL systems. Francis et al suggested that chromatographic or electrophoretic separation was required for accurate determination of the analyte (7).…”

“…Francis et al . suggested that chromatographic or electrophoretic separation was required for accurate determination of the analyte (7).…”